import sys

def calPrize(profit):
    profit_interval = [0,10,20,40,60,100,sys.maxsize]
    prize_rate = [0,0.1,0.075,0.05,0.03,0.015,0.01]
    prize = 0
    length = len(profit_interval)
    for i in range(1,length+1):
        if profit <= profit_interval[i]:
            prize += prize_rate[i] * (profit - profit_interval[i-1])
            return prize
        else:
            prize += prize_rate[i] * (profit_interval[i] - profit_interval[i-1])
    return prize

if __name__ == "__main__":
    prize = int(input())
    print(calPrize(prize)) 